I just bought a pioneer component system from Crutchfield and they said they do not have the adapter to make the tweeter fit in the original spot. Does anyone know where I can get one or how hard and what would I use to fabricate it myself?

Make yourself: jig saw for general shape and some tool to cut the right size hole. Make from 1/4" MDF or something like a cutting board ("plastic" kind, I forget the name of the specific type of plastic).

Get one made by somebody: contact forum members Mr Marv or hookedontronics; or look at TacoTunes.com